On 7/7/21 11:29 AM, Patrick Palka wrote:
r12-1989 fixed the testcase in the PR, but unfortunately the fix is buggy:1. It breaks the case where the common template between the TEMPLATE_DECL t and ctx_parms is the innermost template (as in concepts-memtmpl5.C below). This can be fixed by instead passing the TREE_TYPE of ctmpl to common_enclosing_class when ctmpl is a class template. 2. Even if that's fixed, the analogous case where the innermost template is a partial specialization is still broken (as in concepts-memtmpl5a.C below), because ctmpl is always the primary template. So this patch instead fixes the general problem in a a simpler way that doesn't rely on ctx_parms at all: when looking for the template parameters of a TEMPLATE_DECL that are shared with the current template context, just walk its DECL_CONTEXT. As long as the template is not overly general (e.g. we didn't pass it through most_general_template), this should give us exactly what we want, since if a TEMPLATE_DECL can be referred to from some template context then the template parameters it uses must all be in-scope and represented in its DECL_CONTEXT. This effectively makes us treat TEMPLATE_DECLs more similarly to other _DECLs (whose DECL_CONTEXT we also walk). Bootstrapped and regtested on x86_64-pc-linux-gnu, also tested on cmcstl2 and range-v3, does this look OK for trunk/11?
OK.
PR c++/101247 gcc/cp/ChangeLog: * pt.c (any_template_parm_r) <case TEMPLATE_DECL>: Just walk the DECL_CONTEXT. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-memtmpl4.C: Uncomment the commented out example, which we now handle correctly. * g++.dg/cpp2a/concepts-memtmpl5.C: New test. * g++.dg/cpp2a/concepts-memtmpl5a.C: New test. --- gcc/cp/pt.c | 14 +++++--------- gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl4.C | 2 +- gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5.C | 11 +++++++++++ gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5a.C | 15 +++++++++++++++ 4 files changed, 32 insertions(+), 10 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5a.C diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 7e56ccfc45f..dc0f0b7b58e 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -10728,15 +10728,11 @@ any_template_parm_r (tree t, void *data) break;case TEMPLATE_DECL:- { - /* If T is a member template that shares template parameters with - ctx_parms, we need to mark all those parameters for mapping. */ - if (tree ctmpl = TREE_TYPE (INNERMOST_TEMPLATE_PARMS (ftpi->ctx_parms))) - if (tree com = common_enclosing_class (DECL_CONTEXT (t), - DECL_CONTEXT (ctmpl))) - if (tree ti = CLASSTYPE_TEMPLATE_INFO (com)) - WALK_SUBTREE (TI_ARGS (ti)); - } + /* If T is a member template that shares template parameters with + ctx_parms, we need to mark all those parameters for mapping. + To that end, it should suffice to just walk the DECL_CONTEXT of + the template (assuming the template is not overly general). */ + WALK_SUBTREE (DECL_CONTEXT (t)); break;case LAMBDA_EXPR:diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl4.C b/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl4.C index 625149e5025..f990ae17859 100644 --- a/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl4.C +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl4.C @@ -24,5 +24,5 @@ int main() { A<void>::B::f(0); A<void>::C<int>::f(0); - // A<void>::C<int>::g(); + A<void>::C<int>::g(); } diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5.C b/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5.C new file mode 100644 index 00000000000..3c83bb88485 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5.C @@ -0,0 +1,11 @@ +// PR c++/101247 +// { dg-do compile { target concepts } } + +template<class T, class U> struct A { + template<class> static constexpr bool d = true; + static void g() requires d<U>; +}; + +int main() { + A<int, char>::g(); +} diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5a.C b/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5a.C new file mode 100644 index 00000000000..458f1cdf856 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-memtmpl5a.C @@ -0,0 +1,15 @@ +// PR c++/101247 +// { dg-do compile { target concepts } } +// A variant of concepts-memtmpl5.C that uses a partial specialization +// of A instead of the primary template. + +template<class, class> struct A; + +template<class T, class U> requires true struct A<T, U> { + template<class V> static constexpr bool d = true; + static void g() requires d<U>; +}; + +int main() { + A<int, char>::g(); +}
